US5433909A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making controlled porosity expanded polytetrafluoroethylene products
Assignee: Atrium Medical Corp
•
Filing: 1993-03-12
•
Granted: 1995-07-18
•
Expires: 2013-03-12
Abstract
Abstract A method of forming porous articles with a varying pore distribution by extrusion from a billet with a varying lubricant distribution. A single-polymer polytetrafluoroethylene is extruded and then stretched and sintered to provide a differential porous PTFE structure composed of fibers and nodes connected to one another by these fibers. The microfibrous structure has a portion within the cross-section that possesses a different pore size, accompanied by a different node and fiber geometry, than adjacent areas within that cross section. In a vascular graft, the pores taper inwardly, providing a fluid-tight lumen wall structure that prevents leakage, yet promotes cellular ingrowth and natural tissue regeneration. A node structure of radially-oriented plates provides flexibility, suture strength, and enhanced protection against collapse.
Inventors
- 👤 Paul Martakos
- 👤 Theodore Karwoski
- 👤 Steve A. Herweck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:07
CPC Classifications
B; B29; B29D; B29D23/00; B29D23/001; A; A61; A61F; A61F2/00; A61F2/02; A61F2/04; A61F2/06; A61L; A61L27/00; A61L27/14; A61L27/16; A61L27/50; A61L27/56; B01; B01D; B01D67/00; B01D67/0002; B01D67/0023; B01D67/0025; B01D67/0027; B01D69/00; B01D69/02; B01D69/12; B01D69/1212; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/36; B29C; B29C48/00; B29C48/022; B29C48/03; B29C48/07; B29C48/08; B29C55/00; B29C55/005; B01D2325/00; B01D2325/02; B01D2325/0283; B29C48/001; B29C48/0012; B29C48/0018; B29C48/09; B29C48/10; B29C48/16; B29C48/18; B29C48/19; B29C48/21; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04; B29L; B29L2023/00; B29L2023/005; B29L2023/007; Y; Y10; Y10T; Y10T428/00; Y10T428/13; Y10T428/1352; Y10T428/139; Y10T428/1397; Y10T428/24; Y10T428/24273; Y10T428/249921; Y10T428/249953; Y10T428/249986; Y10T428/249987; Y10T428/24999; Y10T428/249991; Y10T428/249992; Y10T428/31504; Y10T428/3154; Y10T428/31544
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
137 words
A method of producing a shaped porous article, such method comprising the stops of forming a billet of a single fluoropolymer material and a lubricant in which a lubricant concentration gradient has been established along a dimension of the billet, extruding the billet to form an extruded article having a shape and a lubricant component concentration that is varied in level corresponding to the concentration gradient of the billet, removing lubricant from the article and stretching the extruded article form a porous article with predetermined pore sizes in different regions thereof, wherein larger pores are formed in regions where the extruded article had higher levels of lubricant, and sintering the porous article in its stretched state to fix its dimensions thereby forming a sintered porous-article of a single fluoropolymer material having different porosities in predetermined regions thereof.
Claim 2
Independent Claim
137 words
A method of producing a shaped porous article, such method comprising the stops of forming a billet of a single fluoropolymer material and a lubricant in which a lubricant concentration gradient has been established along a dimension of the billet, extruding the billet to form an extruded article having a shape and a lubricant component concentration that is varied in level corresponding to the concentration gradient of the billet, removing lubricant from the article and stretching the extruded article form a porous article with predetermined pore sizes in different regions thereof, wherein larger pores are formed in regions where the extruded article had higher levels of lubricant, and sintering the porous article in its stretched state to fix its dimensions thereby forming a sintered porous-article of a single fluoropolymer material having different porosities in predetermined regions thereof.
Claim 3
Dependent Claim
33 words
The method of claim 1, wherein the step of forming the billet includes forming with a lubricant level that is no lower than about ten percent and no higher than about twenty-four percent.
Claim 4
Dependent Claim
12 words
The method of claim 1, wherein the fluoropolymer is a single-resin fluoropolymer.
Claim 5
Dependent Claim
44 words
The method of claim 1, wherein the billet is formed with lubricant levels that are selected to provide an article having a pore size distribution that permits tissue growth on at least a portion of the article without permitting fluid leakage through the article.
Claim 6
Dependent Claim
26 words
The method of claim 3, wherein the step of sintering is performed to uniformly sinter the porous article at the sintering temperature of said single-resin fluoropolymer.
Claim 7
Dependent Claim
28 words
The method of claim 1, wherein the step of forming a billet includes forming a billet in plural layers, at least two layers having different levels of lubricant.
Claim 8
Dependent Claim
16 words
The method of claim 1, wherein the step of extruding includes extruding a tubular extruded article.
Claim 9
Dependent Claim
34 words
The method of claim 7, wherein the tubular article has a tube axis, and includes a plurality of nodes of flattened aspect oriented transverse to the axis and extending substantially through the tube wall.
Claim 10
Dependent Claim
18 words
The method of claim 8, wherein the tubular article has a wall thickness of under about two millimeters.
Claim 11
Dependent Claim
18 words
The method of claim 9, wherein the tubular article has a wall thickness of under about one millimeter.
Claim 12
Dependent Claim
17 words
The method of claim 10, wherein the tubular article has a wall thickness of about 0.3-0.8 millimeters.
Claim 13
Dependent Claim
23 words
The method of claim 11, wherein the step of stretching is performed by stretching at a rate below approximately two percent per second.
Claim 14
Dependent Claim
23 words
The method of claim 12, wherein the step of stretching is performed by stretching at a rate below approximately one percent per second.
Claim 15
Dependent Claim
26 words
The method of claim 13, wherein the step of stretching is performed by stretching at a rate below approximately one tenth of one percent per second.
Claim 16
Dependent Claim
57 words
The method of claim 1, wherein the step of extruding includes extruding a tubular extruded article having a lumen, and the step of stretching includes stretching so as to produce radially-oriented nodes extending about the lumen and interconnected by fibrils, spaces between the nodes defining through channels from said lumen to an outer surface of the article.
Claim 17
Dependent Claim
15 words
The method of claim 15, wherein the stretching produces nodes having regions of flattened aspect.
Claim 18
Dependent Claim
27 words
The method of claim 1, wherein the step of forming a billet includes forming a billet having different lubricants at different radially disposed positions along its cross-section.
Claim 19
Dependent Claim
14 words
The method of claim 17, wherein the different lubricants are lubricants of different density.
Claim 20
Dependent Claim
14 words
The method of claim 17, wherein the different lubricants are lubricants of different viscosity.
Claim 21
Independent Claim
143 words
A method of producing a prosthesis, such method comprising the steps of forming a billet of a single fluoropolymer material having a lubricant concentration gradient across a dimension of the billet corresponding to a desired porosity structure, extruding the billet to form an extruded prosthesis the extruded prosthesis blank having a distribution of amount of lubrication that varies in correspondence with said concentration gradient of the billet, removing lubricant from the extruded prosthesis blank and stretching the extruded prosthesis blank to form a porous prosthesis blank the stretching introducing predetermined pore sizes in different regions thereof wherein larger pores are formed in regions where the prosthesis blank had greater amounts of lubricant, and sintering the porous prosthesis blank in its stretched state to fix its dimensions thereby forming a sintered prosthesis of a single polymer material having different porosities in different regions thereof.
Claim 22
Independent Claim
143 words
A method of producing a prosthesis, such method comprising the steps of forming a billet of a single fluoropolymer material having a lubricant concentration gradient across a dimension of the billet corresponding to a desired porosity structure, extruding the billet to form an extruded prosthesis the extruded prosthesis blank having a distribution of amount of lubrication that varies in correspondence with said concentration gradient of the billet, removing lubricant from the extruded prosthesis blank and stretching the extruded prosthesis blank to form a porous prosthesis blank the stretching introducing predetermined pore sizes in different regions thereof wherein larger pores are formed in regions where the prosthesis blank had greater amounts of lubricant, and sintering the porous prosthesis blank in its stretched state to fix its dimensions thereby forming a sintered prosthesis of a single polymer material having different porosities in different regions thereof.
Claim 23
Dependent Claim
31 words
The method of claim 20, wherein the lubricant level varies from no less than about ten percent to no more than about twenty-four percent from inside to outside of said billet.
Claim 24
Dependent Claim
26 words
The method of claim 21, wherein the prosthesis is a vascular prosthesis and the lubricant level is selected to provide a pore size for tissue growth.
Claim 25
Dependent Claim
18 words
The method of claim 22, wherein the porosity structure tapers between inside and outside of the vascular prosthesis.
Claim 26
Dependent Claim
107 words
In a method of manufacturing a porous PTFE article having a sintered microporous structure, the improvement comprising forming the article of a single PTFE material mixed with lubricant, wherein a lubricant concentration gradient is established through a cross-section of the article such that the lubricant has different levels at inside and outside, respectively of the article, and stretching the article to achieve a tapered pore structure extending from inside to outside of the article before sintering the article to fix its dimensions, the pore structure extending from smaller pores to larger pores, wherein larger pores are formed in regions where the article has higher levels of lubricant.
Claim 27
Dependent Claim
107 words
In a method of manufacturing a porous PTFE article having a sintered microporous structure, the improvement comprising forming the article of a single PTFE material mixed with lubricant, wherein a lubricant concentration gradient is established through a cross-section of the article such that the lubricant has different levels at inside and outside, respectively of the article, and stretching the article to achieve a tapered pore structure extending from inside to outside of the article before sintering the article to fix its dimensions, the pore structure extending from smaller pores to larger pores, wherein larger pores are formed in regions where the article has higher levels of lubricant.
Claim 28
Dependent Claim
39 words
The method of manufacture of claim 24, wherein the porous PTFE article is a sheet article having a pore size on one surface to define a region of tissue ingrowth, and having a different pore size outside said region.
Claim 29
Independent Claim
128 words
A method of producing a shaped porous article, such method comprising the steps forming a billet of a single fluoropolymer material and a lubricant in which a lubricant concentration gradient has been established which is a step function along a dimension of the billet, extruding the billet to form a single-material extruded article having a shape and a lubricant component concentration that differs in level in different regions of the article in accordance with the lubricant concentration gradient of material in the billet, removing lubricant from the extruded article to form a porous article, and sintering the porous article thereby forming a sintered porous article having different porosities in different regions thereof, wherein larger pores are formed in regions where the extruded article had higher levels of lubricant.
Claim 30
Independent Claim
128 words
A method of producing a shaped porous article, such method comprising the steps forming a billet of a single fluoropolymer material and a lubricant in which a lubricant concentration gradient has been established which is a step function along a dimension of the billet, extruding the billet to form a single-material extruded article having a shape and a lubricant component concentration that differs in level in different regions of the article in accordance with the lubricant concentration gradient of material in the billet, removing lubricant from the extruded article to form a porous article, and sintering the porous article thereby forming a sintered porous article having different porosities in different regions thereof, wherein larger pores are formed in regions where the extruded article had higher levels of lubricant.
Claim 31
Dependent Claim
17 words
The method of claim 26, further comprising the step of stretching the extruded article prior to sintering.
References Cited (Backward Citations)
US2953428A
Cited
US2915786A
Cited
US3094762A
Cited
US3054761A
Cited
US3198691A
Cited
US3473087A
Cited
US3231460A
Cited
US3365355A
Cited
US3265092A
Cited
US3544671A
Cited
US3322608A
Cited
US3407249A
Cited
US3513064A
Cited
US3486961A
Cited
US3634564A
Cited
US3637906A
Cited
US3887761A
Cited
US3664915A
Cited
US3953566A
Cited
US3962153A
Cited
US4187390A
Cited
US3813461A
Cited
US3783057A
Cited
US4209480A
Cited
US4096227A
Cited
US3974526A
Cited
US4061134A
Cited
US4031283A
Cited
US4104394A
Cited
US4225547A
Cited
US4082893A
Cited
US4208745A
Cited
US4234535A
Cited
US4113912A
Cited
US4193138A
Cited
US4277429A
Cited
US4177334A
Cited
US4250138A
Cited
USRE31618E
Cited
US4304010A
Cited
US4303714A
Cited
US4321711A
Cited
US4713070A
Cited
US4332035A
Cited
US4675361A
Cited
US4309776A
Cited
US4850999A
Cited
US4385093A
Cited
US4478665A
Cited
US4576608A
Cited
US4416028A
Cited
US4496507A
Cited
US4442133A
Cited
US4596837A
Cited
US4478898A
Cited
US4643715A
Cited
US4588407A
Cited
US4482516A
Cited
US4598011A
Cited
US4536179A
Cited
US4960423A
Cited
US4760102A
Cited
US4487567A
Cited
US4530113A
Cited
US4550447A
Cited
US4647416A
Cited
US4687482A
Cited
US4563485A
Cited
US4581028A
Cited
US4879135A
Cited
US4619641A
Cited
US4612337A
Cited
US4710331A
Cited
US4923457A
Cited
US4822361A
Cited
US4743252A
Cited
US4820787A
Cited
US5028597A
Cited
US4749585A
Cited
US4867173A
Cited
US4914146A
Cited
US4822352A
Cited
US4743480A
Cited
US5071609A
Cited
US4871361A
Cited
US4824898A
Cited
US4816339A
Cited
US4795459A
Cited
US4911717A
Cited
US4859535A
Cited
US4863442A
Cited
US4909799A
Cited
US4876332A
Cited
US4877661A
Cited
US5026513A
Cited
US5104402A
Cited
US4973609A
Cited
US4882113A
Cited
US4955899A
Cited
US5104400A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-07-17 | 1999-01-16 | 1999-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-17 | 2003-01-16 | 2003-07-18 | $3760.00 | Window Closed / Lapsed |
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